With constant progress in flat panel display technologies, touch screens have been widely applied to display devices such as notebooks, monitors and TVs. By using a touch screen, it is only necessary to touch by a finger symbols or characters on a display screen of a display device to achieve operation of the display device, which makes human-machine interactions more direct. Touch screens also have many other advantages such as robust durability, rapid responsivity, space saving and easy communication.
The touch screens can be divided into three types: out-cell, on-cell and in-cell, according to a difference in positions of touch sensors. For an out-cell touch screen, the touch sensors are directly formed on a display panel, which increases the general cell thickness and decreases the transmittivity. For an on-cell touch screen, the touch sensors are formed on an outer side of a counter substrate of a display panel. Thus, although the general cell thickness is reduced, a process for manufacturing a counter substrate is added. Differently, in an in-cell touch screen, the touch sensors are directly formed inside a display panel, which not only avoids the general cell thickness increase, but also enables manufacture of the touch sensor together with the display panel, thereby simplifying the manufacture process. By virtue of the above advantages, the in-cell technique has been more and more popular in the field of display and has gradually become the mainstream.
Currently, for designs of an in-cell touch screen, there are mainly three types: a resistive type, a capacitive type, and an optical type. According to the existing designs of an in-cell touch screen, touch signal transmission lines are often arranged on an array substrate. As a result, the touch signal transmission lines occupy a certain area of the array substrate, which influences the aperture ratio of the touch display panel.
Chinese patent application No. CN103970353A discloses a touch display panel, wherein touch signal transmission lines are arranged on a counter substrate instead of an array substrate, and wherein two spacers are used to achieve electrical connection between the signal transmission lines and a common electrode on the array substrate in a touch state. In this case, a touch region can be precisely sensed, and the aperture ratio of the touch display panel is ensured since the touch signal transmission lines will not occupy an area of the array substrate.
However, no matter whether the touch signal transmission lines are positioned on the array substrate or on the counter substrate, generally in a method for driving a touch display panel in the prior art, one of the two touch signal transmission lines on axis X and axis Y is used for driving scanning, and the other is used for sensing. In other words, individual drive scanning for touch control is required in this case. Besides, as can be understood by those skilled in the art, in order to drive pixels for display, it is also necessary to apply a drive scanning signal to the gate lines on the array substrate. As can be seen, in a conventional touch display panel, there are generally two kinds of drive scanning: one for driving display and the other for driving touch sensing. Therefore, signal interferences between these two kinds of drive scanning often occur, which gives rise to problems such as imprecise determination of the touch position and low accuracy for the touch display screen.